Objective 6

1. Objective 6 Describe muscle interactions to produce normal muscular movement.

2. Types of Muscle Contractions • Isotonic contractions • Myofilaments are able to slide past each other during contractions • The muscle shortens • Isometric contractions • Tension in the muscles increases • The muscle is unable to shorten

3. Muscle Tone • Some fibers are contracted even in a relaxed muscle • Different fibers contract at different times to provide muscle tone • The process of stimulating various fibers is under involuntary control

4. Muscles and Body Movements • Movement is attained due to a muscle moving an attached bone Figure 6.12

5. Muscles and Body Movements • Muscles are attached to at least two points • Origin – attachment to a moveable bone • Insertion – attachment to an immovable bone Figure 6.12

6. Effects of Exercise on Muscle • Results of increased muscle use • Increase in muscle size • Increase in muscle strength • Increase in muscle efficiency • Muscle becomes more fatigue resistant • You DO NOT get “more” muscle fibers!!!

7. Objective 7 Describe the criteria in naming muscles. Provide an example of each.

8. Types of Muscles • Prime mover – muscle with the major responsibility for a certain movement • Antagonist – muscle that opposes or reverses a prime mover • Synergist – muscle that aids a prime mover in a movement and helps prevent rotation • Fixator – stabilizes the origin of a prime mover

9. Naming of Skeletal Muscles • Direction of muscle fibers • Example: rectus (straight) • Relative size of the muscle • Example: maximus (largest) • Location of the muscle • Example: many muscles are named for bones (e.g., temporalis) • Number of origins • Example: triceps (three heads)

10. Naming of Skeletal Muscles • Location of the muscle’s origin and insertion • Example: sterno (on the sternum) • Shape of the muscle • Example: deltoid (triangular) • Action of the muscle • Example: flexor and extensor (flexes or extends a bone)